The semiconductor industry is the foundation of the trillion dollar electronics industry. The semiconductor industry continues to meet the demands of Moore's law, whereby integrated circuit density doubles every 18 months, in large part because of continuous improvement of optical lithography's ability to print smaller features on silicon. The circuit pattern is contained in the photomask, and an optical stepper is used to project this mask pattern into the photoresist layer on the silicon wafer. 157 nm lies in the region of the spectrum referred to as the vacuum uv (VUV), which range extends from 186 nm down to below 50 nm. Use of this VUV lithography requires materials transparent in this range.
WO 9836324 discloses the use of resins consisting solely of C and F, optionally in combination with silicone polymers having siloxane backbones, as pellicle membranes having an absorbance/micrometer of 0.1 to 1.0 at UV wavelengths from 140 to 200 nm.
French et al, WO 0137044 and WO 0137043 disclose vacuum ultraviolet (VUV) transparent materials exhibiting an absorbance/micron (A/micrometer) ≦1 at wavelengths from 140–186 nm.